This grant focuses on the characterization of two identified genes; the previously described divergent actin, ACT2 and the novel essential gene, NNF1. There is evidence that the divergent action, Act2p, is required for proper nuclear pore complex structure and that Nnf1p has a defect in nuclear envelope morphology, spindle orientation, and mRNA export. These genes will be used to understand more about the organization of the nuclear pore complex and the role of specific proteins within the NPC in nucleocytoplasmic transport, The following questions are to be addressed: 1)Where is Act2p Located? 2) Is NPC organization altered in act2-1 mutants? 3) Is the interaction between Act2p, Nuplp and Srplp direct? 4)What other proteins interact with Act2p?) Is ATP hydrolysis important for Act2p function? 6) Where is Nip Located? 7)Analysis of nnf1t5 alleles. 8) Does Nnflp affect the nucleocytoplasmic GTPase cycle? 9) What proteins genetically interact with Nnflp?